Oh Rainbow Crack Cake, so inconspicuous on the outside, but then BAM! cut a slice of that cake and it’s a party on the inside. Eat a slice of the cake and the party continues in your mouth!!! And soon you find yourself eating half the cake since, like the name says, it’s like crack…
Rainbow Crack Cake
Adapted from Martha Stewart
Yields a 9-in round cake
3 cups all-purpose flour, plus more for dusting
4 teaspoons baking powder
1/2 teaspoon salt
1 cup unsalted butter, room temperature, plus more for buttering
2 1/3 cups sugar
5 large egg whites, room temperature
2 teaspoons pure vanilla extract
1 1/2 cups milk, room temperature
Red, orange, yellow, green, blue, and purple food coloring
White buttercream frosting, or any other white colored frosting you prefer
Preheat oven to 350 degrees. Line two 9-in round cake pans with parchment paper and butter and flour the two pans.
In a large mixing bowl, whisk together flour, baking powder and salt, and set aside. In a mixer fitted with a paddle attachment, cream butter and sugar together until light and fluffy and well mixed. Turning the speed down, add egg whites slowly, making sure the whites are fully incorporated before adding the next. Combine milk and vanilla in a measuring cup. While on low speed, alternatively add the dry ingredients and the milk mixture, starting with the dry and ending with the wet. Mix until just combined.
Divide the batter evenly among 6 bowls (cereal bowls worked perfectly for me). Add food coloring to each of the bowls and stir to combine. Just add enough food coloring to get the desired shades. To create the rainbow effect, start with red and pour the batter into the middle of one of the cake pans, allowing it to spread slightly. Then pour the orange on top of the red batter, making sure you slowly pour it into the middle of the pan and that it spreads the red batter out as well. Repeat with yellow. In the second pan, use the same steps as in the first pan, but start with purple, then add blue and finally green. Transfer pans to the oven and bake for about 30 minutes, or until cake tester comes out clean. Be sure to rotate pans halfway through baking.
Remove pans from the oven and place on a wire rack to cool for about 20 minutes.
Invert cakes and remove from the pan, letting the cakes cool on the wire rack until completely cooled. In the meantime, prepare the frosting.
After the cakes have completely cooled, wrap in plastic wrap and place in the refrigerator for an hour to make frosting the cake easier. Using a serrated knife, level the cakes (and maybe eat the leftover trims!). Place the cake with the purple, blue and green purple side down on a plate. Take about two cup of the frosting and spread it evenly to cover the top of the layer and so it slightly spills off the sides as well. Place the other cake layer, with red side up, on top of the frosted layer. Using an offset spatula, take the remaining frosting and frost the top and sides of the cake to get a nice, smooth, even layer.